This commit adds distributed transaction id infrastructure in
the scope of distributed deadlock detection.
In general, the distributed transaction id consists of a tuple
in the form of: `(databaseId, initiatorNodeIdentifier, transactionId,
timestamp)`.
Briefly, we add a shared memory block on each node, which holds some
information per backend (i.e., an array `BackendData backends[MaxBackends]`).
Later, on each coordinated transaction, Citus sends
`SELECT assign_distributed_transaction_id()` right after `BEGIN`.
For that backend on the worker, the distributed transaction id is set to
the values assigned via the function call.
The aim of the above is to correlate the transactions on the coordinator
to the transactions on the worker nodes.
Comes with a few changes:
- Change the signature of some functions to accept groupid
- InsertShardPlacementRow
- DeleteShardPlacementRow
- UpdateShardPlacementState
- NodeHasActiveShardPlacements returns true if the group the node is a
part of has any active shard placements
- TupleToShardPlacement now returns ShardPlacements which have NULL
nodeName and nodePort.
- Populate (nodeName, nodePort) when creating ShardPlacements
- Disallow removing a node if it contains any shard placements
- DeleteAllReferenceTablePlacementsFromNode matches based on group. This
doesn't change behavior for now (while there is only one node per
group), but means in the future callers should be careful about
calling it on a secondary node, it'll delete placements on the primary.
- Create concept of a GroupShardPlacement, which represents an actual
tuple in pg_dist_placement and is distinct from a ShardPlacement,
which has been resolved to a specific node. In the future
ShardPlacement should be renamed to NodeShardPlacement.
- Create some triggers which allow existing code to continue to insert
into and update pg_dist_shard_placement as if it still existed.
These functions are holdovers from pg_shard and were created for unit
testing c-level functions (like InsertShardPlacementRow) which our
regression tests already test quite effectively. Removing because it
makes refactoring the signatures of those c-level functions
unnecessarily difficult.
- create_healthy_local_shard_placement_row
- update_shard_placement_row_state
- delete_shard_placement_row
Uncrustify 0.65 appears to have changed some defaults, resulting in
breakages for those of us who have already upgraded; Travis still uses
Uncrustify 0.64, but these changes work with both versions (assuming
appropriately updated config), so this should permit use of either
version for the time being.
Before this change, we used ShareLock to acquire lock on distributed tables while
running VACUUM. This makes VACUUM and INSERT block each other. With this change we
changed lock mode from ShareLock to ShareUpdateExclusiveLock, which does not conflict
with the locks INSERT acquire.
MasterIrreducibleExpressionWalker has a copied code from
function check_functions_in_node() which was available with
PG 9.6+. Now PG 9.5 support is dropped we can remove
duplicate code and directly call check_functions_in_node().
Previously we used ForgetResults() in StartRemoteTransactionAbort() -
that's problematic because there might still be an ongoing statement,
and this causes us to wait for its completion. That e.g. happens when
a statement running on the coordinator is cancelled.
That's important because the currently running statement on a worker
might continue to hold locks and consume resources, even after the
connection is closed. Unfortunately postgres will only notice closed
connections when reading from / writing to the network. That might
only happen much later.
Now that there's no blocking libpq callers left, default to using
non-blocking mode in connection_management.c. This has two
advantages:
1) Blockiness doesn't have to frequently be reset, simplifying code
2) Prevents accidental use of blocking libpq functions, since they'll
frequently return 'need IO'
This commit is intended to be a base for supporting declarative partitioning
on distributed tables. Here we add the following utility functions and their
unit tests:
* Very basic functions including differnentiating partitioned tables and
partitions, listing the partitions
* Generating the PARTITION BY (expr) and adding this to the DDL events
of partitioned tables
* Ability to generate text representations of the ranges for partitions
* Ability to generate the `ALTER TABLE parent_table ATTACH PARTITION
partition_table FOR VALUES value_range`
* Ability to apply add shard ids to the above command using
`worker_apply_inter_shard_ddl_command()`
* Ability to generate `ALTER TABLE parent_table DETACH PARTITION`
Adds support for PostgreSQL 10 by copying in the requisite ruleutils
and updating all API usages to conform with changes in PostgreSQL 10.
Most changes are fairly minor but they are numerous. One particular
obstacle was the change in \d behavior in PostgreSQL 10's psql; I had
to add SQL implementations (views, mostly) to mimic the pre-10 output.
Add a second implementation of INSERT INTO distributed_table SELECT ... that is used if
the query cannot be pushed down. The basic idea is to execute the SELECT query separately
and pass the results into the distributed table using a CopyDestReceiver, which is also
used for COPY and create_distributed_table. When planning the SELECT, we go through
planner hooks again, which means the SELECT can also be a distributed query.
EXPLAIN is supported, but EXPLAIN ANALYZE is not because preventing double execution was
a lot more complicated in this case.
Hadi Moshayedi
Onder Kalaci
velioglu
Brian Cloutier
Marco Slot
Jason Petersen
Burak Yucesoy
Murat Tuncer
Andres Freund
Jason Petersen